The invention relates to a synchronous reluctance machine, in particular a motor or a generator of a wind power plant comprising a stator and a rotor which is spaced apart from said stator by an air gap and which is rotatably mounted about an axis, which has an anisotropic magnetic structure, which is formed by flux blocking sections essentially arranged axially one behind the other.
The invention likewise relates to a wind power plant with a generator designed in this way.
As a rule asynchronous machines with cage armatures or synchronous machines are used as dynamo-electric machines, i.e. motors or generators with a power of a few hundred kW and greater. However these machines have a rotor that is complex to manufacture, with a short-circuit cage or a pole winding.
Machines in this power class generally need a cooling of the rotor, since the losses arising there are no longer able to be dissipated solely by convection. Thus the rotor is usually cooled by cooling air, which is generated by self-ventilation or by outside ventilation. Moreover the stator of such a machine must be supplied evenly with cooling air over its entire axial length. With these machines described above a high power factor is frequently demanded, in order to minimize the proportion of reactive power that must be made available to operate the machine.
With dynamo-electric machines of this power class a distinction is essentially made between two types of primary cooling with air. On the one hand there are machines through which air flows only in an axial direction, such as is described for example in DE 2009 051 651 B4. In this invention a circulation of this type is combined with a water jacket cooling of the laminated core of the stator.
Furthermore there are dynamo-electric machines, in which the cooling air also flows radially through the machine, specifically through the stator. In order to make this possible, stator and rotor laminated cores are interrupted by radial cooling slots. This enables the surface onto which the air flows to be significantly enlarged.
Thus DE 10 2012 210 120 A1 describes a dynamo-electric machine with radial cooling slots in stator and rotor and a separate cooling circuit for the winding heads.
Disclosed in EP 2 403 115 A1 is a concept with radial cooling slots for a permanently excited synchronous machine.
A synchronous reluctance machine has the disadvantage, compared to the machines mentioned above, that the power factor is comparatively low and lies at around 0.7 to 0.75. For this reason this type of machine is hardly used at all in the power class of a few hundred kW and greater.
For example the cooling of a reluctance machine of a smaller power and size is described in EP 2 589 132 B1. In this arrangement the cooling air flows axially through flux barriers of the rotor. The stator is fully, laminated in the axial direction.
For machines of greater power this cooling is not suitable inter alia, since the ratio of volume to surface is too small and thus a sufficient cooling surface is not available.